Manufacture of leather.



ADOLPH OBSER, or NEWARK, new JERSEY.

No Drawing. 1

- To all whom) itmay concern:

Be it known that I, ADOLPH OBSER, a citi- Zen of the United States, and a resident of fication.

The invention relates to a new process for treating hides or skins'for the manufacture of leather, and according to said process hides or skins after having been dehaired and prepared for tanning are subjected to the action of a tan bark liquor which serves to perform what may be considered as a preliminary tanning operation. Thereafter the hides which. have been subjected to this preliminary tanning. operationand preferably after being split-are subjected to the action of a pickle or fiber set as it may be called. lVhen the hides or splits have been properly pickled they are subjected to a subsequent or final tanning operation in an acid tanning solution containing a metallic salt, such as a saltor salts of chromium. Thereafter the splits are preferably subjectedto a suitable solution such as an alkalinesolution so as to neutralize the acid in the leather, and thereafter washed. Finally the leather is subjected to a stufling operation in order that there may be incorporated in the leather such fats as are desired. Theleather is also subjected to any other finishing op .as are necessary. The dehaired'hides may or may not have been'subjected to a preliminary pickle prior to starting the tanning operation, but it is desirable to use hides as green as possible. The question of whether the hides have been subjected to a preliminary pickle or salting is dependent. upon whatever steps have been necessary in order that the hides may reach the tannery in proper condition. The dehaired hides are placed in tan bark liquor or bark tanning manurnc rurm or LEATHER.

as it is frequently referred to. The preferred manner of doing. this is to place the hides in rotating or reciprocating drums so that all portions of each hide will be sub,- jected to the action of the tanning solution within the drums These drums are frequently referred to by tanners as the rock- "ers". In tannin cow hides for exam is they are subjected to the action in the tan bark liquor or bark tanning solution I for from seven to'ten days,'dependent more or less upon the thickness of the hide and the strength ofthe bark tanning ,solution. In other words, the hides remain in this tanning solution about twenty five per cent. less time than is required where the hides are to be tanned entirely with the bark tanning solution. The bark tanning solution maybe referred to as a preliminary tanning solution, since there is effected in this solution only a preliminary tanning or partial tanning operation. After the hides have been removed from the bark tanning solution, and when a large percentage of the moisture (viz., the tan bark liquor) iii the hides has been eliminated, as.by running through a'wringing machine which would leave the hides damp or wet, they are pref- V erably split four or fi've times.

The splits are then subjected to the action of a pickle or fiber set; This pickle consists of rock or common salt, Gla'uber salt and sulfuric acid. For example, for one hundred pounds of split hides there is employed a pickling solution consisting of six pounds of rock or common salt, one pound of Glauber salt,

and one half pound of sulfuric acid of sixty SlX per cent. strength. To this there is added about sixteen gallons of water. The leather resulting from the splits is suitable for upholstery of automobiles and the like.v

The weight of the hides or splits which are sub ected to the pickle is taken when the hides or splits are in What may be considered as a dry pressed condition. In other words, when they are moist'but when a large percentage of the moisture has been removed therefrom as by pressure. The split hides remain in this-pickle for from onechalfhour to one hour, dependent upon the thickness of the 'split. At the end of this period there is added to the pickle a s0- Speclficationof Letters Patent. Patented June 11, M918, Application filed April 18, 1917. I Serial No. 162,929.

lution which provides the metallic salts;

whereby a subsequent or final tanning operation can take place. The solution containing these metallic salts may be referred to as the standard or the stock solution which, asthe name implies, should be kept on hand where the present invention is employed. This standard or stock solution is made as follows:

There is first made .a liquor comprising four and two tenths pounds of chrome soda (bichromate of soda) 0r the proper amount of a bichromate of potash may be used as the chemical equivalent of the sodium chromateand two and twenty-five one hundredths pounds of wheat white flour. .There is finally slowly added sulfuric acid of sixty six per cent. strength, until four and onehalf pounds of acid have been added. The

resulting solution is allowed to stand about an hour and a half. After it has stood this length of time it can be kept an indefinite length of time prior to bein used. An amount of standard solution w ich is equal to the amount of standard solution resulting from the amounts of ingredients just specified, is then placed in the pickle that is in the rockers or drums when the splits in the rockers or drums have been subjected to the ickle for the proper length of time, and a ter the standard solution has been added the split hides are allowed to remain for about four or five hours so that-a subsequent 0r final tanning operation will take place.

The amount of materials above designated are the proper amounts for the tanning of one hundred pounds of the dry pressed splits. But it will be obvious that in the actual manufacture of standard solution, large quantities will be made at once and it is quite likely that the standard solution or composition will be sold to the users rather than being madeb the users themselves. When the standar solution is mixed with the pickle solution already in the rockers, the resulting mixture is an acid solution containin chromium salts. The splits remain in t e subsequent or final tanning solution for about four or five hours during.

a which time the chromium acid or tan liquor is released from the chrome salts in the solution due to the acid contained in the solution or mixture within the rockers. A function of thefiber set liquor is to prevent the bark tannin r from burning through the splits. The pickle to which the splits were subjected prior to the final tanning opera tion just referred to, may be considered as an aqueous solution formed of sodium salts (common salt and Glauber salt) and sulfuric acid.

At the end of the subsequent or final tanning operation the tanning liquor within the rockers or drums is Withdrawn andwater at action within the drums for a period of about ten minutes.

The hides are then subjected for about ten minutes to an alkaline solution so as to counteract the acid remaining in the splits. This alkaline solution is made by adding to Water one and a half to two per cent. of borax, soda or any other suitable alkali, that is, one-half to two pounds of alkali per hundred weight of split hides. After the alkali treatment there follows a second washing for about ten minutes so as-to remove any portions of the alkali solution, whereby the splits will be left in a neutral condition, that is, neither acid nor alkali. A large portion of the moisture mostly water in the split hides may now be removed as by wringing, or it may be left in the washed split hides, and they are ready to be subjected to the fat liquor or stufiing operation, as this fat treatment is frequently called, whereby the proper fats may be introduced into the hide dependent more or less upon the particular use to which the final leather is intended. The fat solution which is preferably employed is an aqueous solution comprising as a component part thereof salt, cottolene, an what is known in the trade as waterless moellon. Cottolene is a mixture of fats and cottonseed oil but in place thereof any suitable sulfurated grease or oil can be used; as, for exam le a rease or oil from neats foot oil or any heavy vegetable oil, such as castor oil or cottonseed oil. In the fat liquor comprising these ingredients the leather is allowed to remain for about half an hour after which the leathers are removed from the liquor and allowed to dry in any suitable manner, and

they are also subjected to any other suitable finishing treatment desired. During the time that the hides or splits are being treated, as in the preliminary tanning operation, the pickle, the subsequent tanning operations, the several washes and the fat supplying or stufiing operations, the hides or splits are agitated or the containers are being be performed by removingthe hides or splits being treated from one set of rockers or containers, to subsequent sets in which the required solutions for performing the required steps of the process are contained. It is impossible, for instance, in the bark tanning operation, to accomplish a uniform tanning or partial tannin of the hides. There will be spots of the hi e which will be practically limited to the precise method herein shown be perand described, as the invention may epartmg formed in various ways without from the spirit and scope thereof.

What I claim is 1. In the manufacture of leather the method which comprises subjecting hides to a preliminary tanning o eration in a barktanning liquor, therea ter splitting and v picklin said hides and subjecting the splits to a su sequent tanning operation in a metallic tanning liquor.

2. In the manufacture of leather the method which comprises sub-jectinga hide to the action of a bark-tanning liquor, subsequently splitting and pickling said hide and subjecting said pickled. splits to the action of an acid metallic tanningliquor.

'3. In the. manufacture of leather the method which comprises subjectin dehaired hides to the application of 'a bar tanning solution, subsequently splittin the hides and thereafter pickling said sp its, subjecting said pickled splits to a subsequent tanning operation by the application of an acid metallic tanning liquor until the tanning is completed, neutralizing the tanned splits by the application of an alkaline solution, and

finally xashing the splits and dressing the.

same.

4:. In the manufacture of leather the method which comprises subjecting a hide to the effect of a bark-tannin solution so as to partially tansaid hide, t-ereafter splitting said hide, -pickling said splits and subjectingsaid pickled splits to a subsequent tanning operation in an acid chrome tanning liquor, washing the splits, neutralizing any acid remaining in said splits by an alkaline solution, washing the splits so asto remove anyremaining alkaline solution and finally finishing the leather.

5. In the manufacture of leather the method which comprises subjecting hides to a partial bark tanning, splitting said partially bark-tanned hides, pickling said splits in an aqueous solution containin rock or common salt, Glauber salt and sul uric acld,

thereafter subjecting said splits to a final tanning operation in a solution comprising said pickle to which there has been added an aqueous solution formed from bichromate of potash or chrome soda, wheat flour and sulfuric acid, washing said tanned splits and finall dressing.

6. In the manufacture of leather the method which comprises pickling a partially bark-tanned hide and thereaftersubjecting said partially bark tanned pickled hide to a final tanning operation in a solution to which there has been added solution formed by the chemical reaction resulting from bichromate of potash or chrome soda, wheat n, flour and sulfuric acid inthe presence of water.

7. In the manufacture of leather the method comprising subjecting a split from a hide partially tanned by a bark-tanning tothe action'of a pickle or fiber set in which pickle there is rock or common salt, Glauber salt and an acid, subjecting said pickled split to a final tanning by the adding to said pickle a solution or mixture formed from a metallicbase and an acid, subjecting the tanned splits to an aqueous alkaline solution, subsequently washing said splits and thereafter subjecting said splits to the ac-' tion of a fat liquor.

8. In the manufacture of leather the method. which comprises taking a pickled split which is partially tanned by a barktanning. liquor the picklin for which was performed after. the partial bark-tanning operation and subjecting said-pickled split to a final tanning operation in an aqueous solution formed of rock or common salt, Glauber salt andsulfuric acid to which there has been added a stock solution formed of a water-paste comprising bichromate of potash or chrome soda and wheat flour and to which paste there has been added sulfuric acid, allowing the splits to remain in the mixture or solution resulting from the adding of the stock solution to the pickle until the tanning is completed, thereafter neutralizin the effect of the acid in the splits and finishing.

9. A solution for use in tanning which solution is made by mixing, in, water, approximately 4.20 pounds of chrome soda and approximately 2.25 pounds of wheat white flour and by adding to the mixture sulfuric acid. I

10. A standard or stock solution for use .in tanning whichfsolution is made by comby adding slowly to the mixture sulfuric 0 acid until there is contained in the mixture the amount of sulfuric acid that is equivalent to that contained in 4.5 pounds of acid of 66- per cent. strength.

12. In the tannin .of leather the method which comprises su jecting 'dehaired hides to bark tanning for about 75 per cent. of the period required to effect a complete tanning of the hides by said tanning liquor, split ting the partially tanned hides,- pickling the splits in an aqueous solution containing rock or common salt, Glauber salt and sulfuric acid for a period sufiicient to set the fiber in the splits, adding to said pickle an aqueous stock solution formed of bichromate of potash or chrome soda mixed with fiour and to which sulfuric has been added, allowing the hides to remain in the solution resulting from the pickle and stock solution until completely tanned, thereafter causing the tanned hides and tanning liquor to be separated from each other, washing the tanned splits, subjecting the washed splits to an alkaline solution, and thereafter again washing the splits in water, subjecting the washed splits to a fat liquor and finally finishing the leather.

' 18. In the manufacture of leather the method which comprises subjecting hides to a bark-tanning solution, splitting the hides, pickling the partially tanned splits in a solution containing sodium salts and an acid, subjecting the pickled splits to a tanning solution formed of sodium salts, an acid, a chrome base, wheat flour and water, subsequently washing the tanned splits and neutralizing the acid therein, and ultimately stufling the splits.

14. In the tanning of. leather a method which comprises sub ecting hides to a partial bark-tanning operation, splitting said partially tanned hides, picklin said splits so as to set the fiber therein, su jecting the pickled splits to a subsequent chrome tanning operation, washing and stufling said hides.

15. In the manufacture of leather the method which comprises a preliminary bark tanning, a mechanical removal of a large percentage of the bark tanning liquor, a pickling, a metallic tanning and a finishing.

16. In the manufacture of leather splits the method which comprises subjecting a hide to a preliminary bark tanning, splitting and pickling the partially bark tanned hide, subjecting the pickled splits to a subsequent metallic tanning solution and finally Y finishing the splits.

17. In the manufacture of leather the method which comprises partially tanning hides, splitting the same, pickling the partially tanned splits, subjecting'the pickled partially tanned splits to the action of a chrome tannin solution, washing the tanned splits and sub ecting the tanned splits-to a fat liquor.

' 18. In the manufacture of, leather splits the method which comprises a preliminary bark tanning operation and a subsequent pickling operation, a subsequent or final tanning operation in a chrome acid tanning solution, neutralizing and washing operations so that no free acid or free alkali will remain in the leather, and a stufling operation in a fat liquor.

19. In the manufacture of leather the method which comprises subjecting a hide to a preliminary tanning operation in a bark-tanning liquor, thereafter splitting said partially tanned hide, subsequently pickling said partially tanned splits, and thereafter subjecting said pickled splits to a tanning operation in a metallic tanning liquor.

20. In the manufacture of leather the method which comprises forming tanned leather splits and subjecting the leather ing leather said liquor comprising salt, oil

and waterless moellon.

24. An aqueous fat liquor for use in stuifing leather said liquor comprising salt, cottonseed oil and waterless moellon.

Specification signed and witnessed this 16th day of April A. D., 1917.

ADOLPH OBSER.

Signed inthe presence of HENRY G. DICKENSHEETS, BEBFOR OBSER. 

